Cultivation hints
Mesembs cultivation
The main distribution area of Mesembs is South Africa and Namibia and here especially in the winter-rainfall-area along the west coast. Many Mesembs (e.g. all Conophytum, Argyroderma and Cheiridopsis) are used to get rains in winter thus belonging to the short-day-plants. In the northern hemisphere the start to grow as days get distinctly shorter in late summer and fall. Long-day-plants (e.g. Lithops, Faucaria or Glottiphyllum) have an additional growing period in spring.
Light
As with most all Succulents Mesembs need high light intensities all year round and should not be staged underneath benches or hanging pots. In contrast to nature plants will get sunburned rather quickly in cultivation because of a lack of sunlight during winter causing deficiency in protective pigments. High loss may occur especially during the first hot and sunny days in spring. Do shade your plants but only during hours necessary. Proper ventilation and good feeding will lessen burning danger.
Watering
In nature parcipitation ranges from > 2,000 mm/a in the south to nearly zero in Namibia.
Especially in the dry regions plants depend on water from fog occurring there most any
day in the morning. Plants can uptake the water through very fine roots close to the
surface. Daily misting as many people do will only be useful if done early as the
plants need hours to take up the water. Spraying at 8:00 in the morning in summer is
nonsense as the water will be gone within minutes. So if you don't like to get up at
3:00 forget your mister, take your can or hose and give plenty of water whenever your
pots get dry. If you keep Mesembs dry during their resting time there will be high
loss but very little if you water them.
The water should be free of calcium and at least as warm as the substrate. On a warm
summer evening your water should be 25° C. Do water from above and several
times a year so strong that most of it runs away through the bottom holes of your
pots. If not, salts and other poisonous materials that plants give into the
ground via their roots will accumulate and will reduce both growth and the beauty of
your plants.
Nutrition
As with all plants Mesembs need nutrition. All macro elements (N, P, K) and microelements
(Mg, Fe, Fn, Bo, ...) must be available in the quantity necessary. They must also be
present in soluble form so that the plants can take them up. It is useful to give a
microelement feeder into the potting mix anytime you transplant (every 2 - 4 years)
and a high nitrogen liquid feeder on low concentration several times a year during the
growing season. You will have a regular and constant growth if you feed frequently on
low concentration.
As substrates you may use any well draining materials on particle size between 1 and
4 mm. Avoid any dust, especially loam. The latter will kill any plants with time. We
use pumice. Check your pH-Level! It should be between 6 and 7, never > 7.
Pests
There should never be any pests. In case you find any do treat your entire collection. You can reduce this by taking care and treating against major pests (e.g. root-mealy-bug) in advance. With Imidacloprid (in Confidor or Lizetan) we have a pesticide with an efficacy never seen before being not at all poisonous to humans and nearly free of any smell and you cannot only reduce costs of about 10% compared to traditional substances (e.g. E605) but you will have your collection free of any bugs with just 2 treatments per year. This is not efficient against red-spider-mite but you don't have them anyway if you water from above.
Lithops cultivation
For the past 20 years that I have been growing Lithops I have tried various soils,
temperatures, shadings etc. and I ended up with a way that at present works best
for me. This will be outlined here briefly. It is important to know that it works
for me under conditions here in the very west of Germany and it may not work best
elsewhere.
Lithops are usually grown from seed. They can be propagated from cuttings but rooting
them is more difficult than it is with Conophytum. Furthermore this requires large
plants to take cuttings from. As Lithops grow slowly and do not multiply heads every
year large old plants are rare and valuable.
Sowing Lithops in autumn is rather easy. Seed is best stored for at least one year as fresh seeds
may germinate too irregular. Lithops seeds keep viable for at least 10 years if stored
in the fruit in a dry dark place.
For sowing it needs a free draining mineral substrate. I use pumice with no ingredients
at all but if you have no access to pumice any stone gravel of 1 – 4 mm size will
do if the pH-value is not above 7. I strictly avoid to use any peat or pot ground as most
pests need this to survive. Furthermore all very fine particles are avoided to make
sure that seedling roots can grow into the soil directly instead of creeping over the soil.
Before sowing the soil should be sterilized to avoid any weeds to germinate. This is
easily done in an oven at 200°C for one hour. This is filled in pots or trays and made
completely wet with rainwater. If tap water is used it should not contain calcium.
Seeds are scattered on top of the wet soil. Seeds are not covered with soil. Optimum
density is about 10,000 seeds per square meter. Pots or trays are covered with a thin
plastic and kept in a shady place at a constant temperature of about 15°C (not over
20°C). A windowsill in a temperature-regulated room gives better germination
than a sowing in a greenhouse. It is too hot and too sunny there and days are warmer
than nights. After two weeks germination has finished and the containers can be uncovered.
Seedlings are sprayed several times a day and will not be allowed to dry up at all for
the first few weeks. More light is given very slowly and full sun during hot days is
avoided for the first year. No chemicals of any kind are used for sowing. No fertilizer
is given before seedlings are one year old. As plants grow larger they can have more
light but on hot sunny days Lithops require shading all their life. If you live in a
sunny climate this may not be needed but after a dark German winter Lithops will die
in full spring sun within an hour.
Lithops can be grown under permanent shading as it is done in large nurseries but
plants grow fast and large and tend to become long and soft. Coloration is very bad
under such conditions. If you have ever compared a fat green Lithops dorotheae with
a small natural one with black-red markings on an orange-yellow body grown in full
sun you will know the difference. This is why I give shading during hours necessary only.
Lithops need very little feeding. I use liquid fertilizer (Wuxal Super, N:P:K = 8:8:8)
2 – 3 times a year during growth. I tend to water more than most growers do but to
be on the safe side I suggest not to water during hot summer conditions and I keep
them dry from December to around April.
Pest control is done by one treatment of Imidachloprid (trade name Confidor in Germany)
per year during plant growth. That’s it. No other chemicals are used. If any trouble
occurs conditions need improvement.
Except for the germination process itself Lithops like warm days and very cool nights.
In winter I keep them under automatic frost protection but this has failed a few times
and no Lithops has died at -6°C for two nights in a row.
Lithops grown slowly under maximum light will flower for the first time at three years
of age. One can do it within one year but there is little chance to get them through
the next winter. One can easily make his own seeds. If you like surprise let insects
do the job. If you like it true to type keep insects away and take a paint brush (a
different one for any item please!). Most any Lithops can be crossed within any other
one and insects do not care at all.
Lithops grown in small pots may need repotting every few years but if they grow in
larger trays they can stay there for many years untouched provided watering is
done from above and excess water can just run away. Again I use pumice for all
potting. During repotting all roots are cut away except for a 2 – 3 cm rest of the
main root. This way plants make new roots much faster and it is assured that roots
are straight in the new pot. A plant with a long root potted bent dies slowly.
You can clean heads from old sheaths but If one has old plants with thick layers
of old sheaths it is safer to keep them on the plant. Otherwise heads easily break
off. If this happens put broken off head into soil immediately, make it moist and
keep it below 15°C.
In this short article I have rather mentioned different aspects than described
them in detail. Any reader wishing more information feel free to get in touch with
me in German, English, Dutch or Afrikaans. Sorry no French.
Lithops cultivation under tropical conditions
In their natural habitats Lithops have warm or hot days but cold nights
down to freezing point and day length is short in winter and long in
summer. This is what Lithops naturally are adapted to. Here in Germany
it is similar. The main difference is that in South Africa and Namibia
where Lithops grow it is sunny most every day but here a sunny day is
an exception and winters have times of strong frost.
Although I have no experience myself growing Lithops in tropical countries
where it is hot day and night, humidity is high and day length is similar
winter and summer. I have several customers in different tropical countries
who have tried. It turns out that Lithops rather easily adapt to very
different conditions.
They do need a period of short days once a year that should last for two
months at least. This can rather easily be achieved by giving normal
daytime conditions for some hours and covering them for the rest of the
day to make it dark. For doing so start at the given 12 hours daylight
and reduce this by one hour per week until you reach 8 hours daylight.
Keep this for a few weeks and increase again by one hour per week until
you are back at normal conditions. This simulates a winter and makes
sure that there is the needed resting time. It also ensures that
flowering occurs. If you have 12 hours daylight all year round your
plants will always grow but they will not survive this for longer
than 2 – 3 years and it is unlikely that you will see flowers.
The most difficult aspect is high night temperatures. Lithops are used
to night temperatures between zero and 10°C all year round. You do not
have this at all. I know of someone who puts his Lithops into a
refrigerator during night. This works but if you hold a large collection
this of course is rather a joke than reality.
Try at least to give as much air circulation and use the coolest place
you have. Some light spray with water also makes it colder for the
plants. This however again increases air humidity and this is too high
anyway. Be creative as there is no limit for ideas. For any other
aspect of cultivation I see no difficulties.
Lithops live in arid conditions so they will need rain protection. Take
care not to increase temperatures and humidity by giving this. Just some
roof, no side glazing. Make sure soil dries out before next watering.
Shading might be necessary especially if you acquired new plants grown
under different conditions. Protect them from too much direct sunlight
until they got used to.
Sowing in autumn might be difficult as germination decreased as temperatures get
higher than 20°C. (shady place, 15°C)
A plant usually tells you what is wrong. If bodies burst it is too wet
all the time. Make it as dry as you can. If the new bodies push through
the old ones before they have dried out they grow too fast and the
dormant period is missing or too short. If no flowers occur it again
is a matter of day length.
If rotting is a frequent occurrence, do all you can to reduce humidity.
Give best possible air circulation and avoid any organic matter in your
potting mix. Any fine stone gravel will do as long as its salt-content
is not too high. Using fungicides should only be done if any improvement
of conditions fail.
There is one main advantage that you have. You don’t need any greenhouse
that needs most of your income to heat them through long dark frosty winters.
There is no reason not to try these plants and I would be very glad for
any communication on whatever experience you have made.